net: ehea: avoid null pointer dereference

BugLink: https://bugs.launchpad.net/bugs/1878232

commit 1740c29a upstream.

ehea_get_port may return NULL. Do not dereference NULL value.

Fixes: 8c4877a4 ("ehea: Use the standard logging functions")
Signed-off-by: Heinrich Schuchardt <xypron.glpk@gmx.de>
Acked-by: Thadeu Lima de Souza Cascardo <cascardo@debian.org>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Ian May <ian.may@canonical.com>
Signed-off-by: Kleber Sacilotto de Souza <kleber.souza@canonical.com>

drivers/net/ethernet/ibm/ehea/ehea_main.c

@@ -1169,16 +1169,15 @@ static void ehea_parse_eqe(struct ehea_adapter *adapter, u64 eqe)
 	ec = EHEA_BMASK_GET(NEQE_EVENT_CODE, eqe);
 	portnum = EHEA_BMASK_GET(NEQE_PORTNUM, eqe);
 	port = ehea_get_port(adapter, portnum);
+	if (!port) {
+		netdev_err(NULL, "unknown portnum %x\n", portnum);
+		return;
+	}
 	dev = port->netdev;
 
 	switch (ec) {
 	case EHEA_EC_PORTSTATE_CHG:	/* port state change */
 
-		if (!port) {
-			netdev_err(dev, "unknown portnum %x\n", portnum);
-			break;
-		}
-
 		if (EHEA_BMASK_GET(NEQE_PORT_UP, eqe)) {
 			if (!netif_carrier_ok(dev)) {
 				ret = ehea_sense_port_attr(port);